Electrically-heated steam boiler



May 22, 1928.

C. W. CAMPBELL ELECTRICALLY HEATED STEAM BOILER Filed April 1926 ATTORNE Y.

Patented May 22, 1928.

UNITED STATES PATENT OFFICE.

CLBLETOH W. CAMPBELL, OF DENVER, COLORADO, ASSIGNOB TO MOL'L MANUFACTUR-ING COMPANY, 01 DENVER, COLORADO.

ELECTRICALLY-HEATED STEAM BOILER.

Application flied April 8, 1926. Serial No. 100,548.

This invention relates to an electrically.

heating element, for insertion in the tubes of the boiler, which will beeconomical to 1118.11, ufacture, eflicient in operation, long wearing,and easy to install.

Another object of the invention is to so construct the heatin elementthat it will bring the heating coil into close proximity with the watersurface of the boiler without intervening material of any nature, sothat the heat will be quickly transferred to the water with little lossand yet the coil will be prevented from contacting with the tube.

A further object is to construct the supportin frame of the heatingelement in a plurahty of co-acting sections, so that it will withstandthe expansion, contraction and distortion due to the heating.

A still further object is to secure all of the tube heating elements toa common base held in place by a single nut, so that they ma allbe-removed simultaneously;

(d ther objects and advantages reside in the detail construction of theinvention which is designed for economy, simplicity and efli ciency.These will become more apparent from the following description.

In the following detailed description of the invention, reference isbad. to the accomanying drawing which forms a part hereof.

ike numerals refer to like parts in all views of thedrawing andthroughout the description.

In the drawing:

Fig. 1 is a vertical section through the lower portion of a boilershowing the invention in place therein. In this view, two of the boilertubes are cut by the section; in the left one, the heating element isshown in elevation and,'in the right one, in longitudinal section.

Fig. 2 is a plan view of the base member used to support the heatingelements.

Fig. 8 is a perspective view of one of the heating element units.

Fig. 4 is a cross section through the boiler, taken on the line 4-4,Fig. 1.

Fig. 5 is a. bottom view, looking upward, of the base member and itsconnections.

Fig. 6 is an enlarged detail section through one of the heating coils.

The boiler is illustrated at 10, provided with a plurality oflongitudinal boiler tubes 11, which are swedged into a head 12, rivetedto the boiler, as shown at 13. Welded to the center of the head 12, is astud bolt 14 for supporting the entire heatin device.

The heating device comprises a hase 15, provided with a series ofcountersunk openings 16 corresponding in spacing and number to theboiler tubes 11. Longitudinal bolts 17 pass through these openings 16and clamp a series of units 18 to the base 15; there being concentricholes 42 formed in the units for the passage of the bolts 17. An opening39-is formed in the base for the reception of the stud 14 which carriesa nut 31 for clamping the base 15 to the boiler lfead 12. At the bottomof the series of units 18, a base unit 19 is placed having a projectingflange around its central opening which extends within the countersinkof an opening 16'. At the top of the series of units, a cap unit 20 isplaced provided with a passage 21 for one terminal of the heating coil.All of the units and base 15 are formed of porcelain or similar heatresisting and electrical insulating material. The bolt 17 is clamped tothe series of unitsby means of a nut 22 before being clamped to the basemember 15 by means of a second nut 23.

One of the units 18 are illustrated in detail in Fig. 3. Each of theseunits comprise an odd number of longitudinal passages 24, opening to theexterior of the unit through slots 25, along the side of which retainingflanges 43 are formed. The

partitions between the passages 24 are notched at top and bottom asshown at 26 so as to allow the heating coil wire to pass from onepassage to the next at the extremities of the series.

The heating coils are formed of any suit able resistance wire and areillustrated at- 27, there being a single length of coil in each seriesof units. One extremity of the coil passes through the bottom member 19,as show at 28, to a terminal bolt 29. The coil then passes upwardly inone of the passages 24 through the topmost notch 26 to the next adjacentpassage 24, thence downward- 1y. In this manner, the entire series. ofunits is completely surrounded by a series of longitudinal heatingcoils, the last coil terminating at the top of the series through thepassage 21 to a connection under the head of the bolt 17. The bolt thusserves as an electrical conductor to return the current to the bottom ofthe base plate 15.

At the bottom of the base 15, all of the bolts 17 are connected togetherby means of bus bars 32 and all of the terminal bolts 29 are connectedtogether by means of bus bars 33. The bus bars 32 receive current from acommon binding post 34, carried in an opening in the base, and the busbars 33 receive current from a similar binding post 35, carried in anopening 41 in the base. This method of connecting places the heatingcoils in parallel so that the failure of one coil does not affect theremaining coils.

The heads of the terminal bolts 29 are carried in depressions 36 in thebase plate which are of a sufficient length to pass under the base unit19 to receive the terminal of the heating coil. Each of the units 18,the bottom member 19 and the top member 20 are provided with projectingflanges 37 at one end and a countersink 38 at the other so that they areself-aligning, when placed in a contacting series.

It is desired to call attention to Fig. 6, where it will be noted thatsubstantially the full heating coil is directly exposed to the surfaceof the boiler tube 11, without intervening insulating material. Thesides of the passages 24 project only sufliciently over the coil tomaintain it in place and prevent accidental contact with the boilertube.

While a specific form of the improvement has been described andillustrated herein, it is desired to be understood that the same may bevaried within the scope of the appended claims, without departing fromthe spirit of the invention.

Having thus described the invention, what I claim and desire secured byLetters Patent is:

1. An electrical heating element for steam boilers having fire tubesopening to one extremity of said boiler comprising a base of insulatingmaterial; a plurality of standards each composed of a series ofinsulating units projecting from said base and maintained in spacedrelation thereby, said relation coinciding with the spaced relation ofsaid fire tubes; heating coils carried by said standards; and means forsecuring said base in position against said boiler with said standardsextending within said heating tubes.

2. In a heating element having a series of insulating units securedtogether by means of a concentric bolt, said units being provided with aseries of longitudinal grooves opening to their exterior; means forallowing communication between said grooves comprising a concentricseries of notches in the end of each of said units, each of said notchescommunicating between two of said grooves.

3. An electrical heating element for steam boilers having fire tubesopening to one extremity of said boiler comprising a base of insulatingmaterial; a plurality of standards each composed of a series of insulating units projecting from said base and maintained in spaced relationthereby, said relation coinciding with the spaced relation of said firetubes; heating coils carried by said standards; and means for securingsaid base in position against said boiler with said standards extendingwithin said heating tubes, said means comprising a stud secured to andprojecting from one extremity from said boiler and adapted to passthrough said base of insulating material and a nut adapted to bethreaded on said stud so as to draw said base toward said boiler andmaintain said standards within said tubes.

In testimony whereof, I afiix my signature.

GARLETON W. CAMPBELL.

